Boris Johnson pledges to introduce driverless tube trains within two years

This would mean the majority of the network would be served by driverless trains by the end of the decade.

Mr Johnson added: “The revenue that comes into the DLR from automation, from making sure that you don’t have personnel doing things that are unnecessary, greatly exceeds the cost of running it.

“You can use that revenue to invest in new systems. I want to be the mayor who delivers that.”

Mr Johnson has previously had to contend with 23 London Underground strikes during his four years in office.

The RMT union described driverless trains as “lethal and unworkable”, while Aslef, Britain’s biggest drivers’ union, said it would “vigorously” fight any attempts to eliminate the need for drivers.

"I want to stress that in making these reforms of the Tube, I believe it's going to be possible to work with the unions,” he said.

In a thinly-veiled attack on his rival Ken Livingstone over his links with transport unions, Mr Johnson added: “There may be some union bosses who won't agree but I'm not funded by them and I'm not supported by them."

Mr Johnson also refused to rule out running for a third term as Mayor despite claims of a bid for the Conservative Party leadership.

He said he "regrets" previously saying he would serve a maximum of two terms.